Device for plotting flat blanks to form tubular transition pieces



C. R- LEFFLER DEVICE FOR PLOTTING FLAT BLANKS TO FORM TUBULAR TRANSITIONPIECES Oct. 26, 1954 2 Sheets-Sheet 1 Filed Nov. 14, 1949 CHFIELESLEFFLE/Q.

W ?%0%@, r a? ornegs Oct. 26, 1954 Q LEFFLER 2,692,434

DEVICE FOR PLOTTING FLAT BLANKS TO FORM TUBULAR TRANSITION PIECES FiledNov 14, 1949 2 Sheets-Sheet 2 luventor E CHAR/.55 L'FFLge H fly mlmyattorneys Patented Get. 26, 1954 DEVICE FOR PLOTTING FLAT BLANKS TO FORMTUBULAR TRANSITION PIECES Charles R. Lefiler, Redwood City, Calif.,assignor of one-fourth to Wayne R. Millington, Redwood City, Calif.

Application November 14, 1949, Serial No. 126,963

Claims.

This invention relates to a device for plotting on a flat sheet ofmaterial the opposite end edges of a transition piece to be subsequentlybent to tubular form for providing a connection between a pair ofopenings.

In sheet metal work, the operation of forming a transition piece forconnecting two ducts or conduits of different diameters, or of differentshapes and sizes and which openings or ducts may have their central axesoffset relative to each other and at different angles, has heretoforebeen a laborous, time consuming, expensive job, and in many instances,the final result is quite lacking in accuracy. Such transition piecesare first outlined on fiat sheet metal and after cutting the piece fromthe sheet it is bent to tubular form and the adjacent edges are securedtogether in any suitable manner, such as by crimping or by soldering,welding or riveting.

The main object of the present invention is the provision of a simple,economical, easily operated device that enables a skilled or even anunskilled workman to quickly plot the end edges of any desiredtransition piece on a fiat sheet of material. This device is adapted toaccomplish in minutes, and with absolute accuracy, what formerlyrequired hours.

Another object of the invention is the provision of an improved methodfor plotting the end edge of a transition piece on a fiat sheet ofmaterial.

In the statement that the present invention is adapted for use inquickly plotting the end edges of any desired transition piece, it is tobe understood that this includes transition pieces for openings the axesof which may not be ccaxial nor parallel, and the outlines of which maybe quite difierent and of different areas. For example, the axes of theopenings that are to be connected by a transition piece may be indifferent levels and laterally offset and at any angle to each other andone may be poly-sided while the other may be circular or oval. Thespacing between the openings may be any reasonable distance where atransition piece is normally employed, The complexity of the problemdoes not increase the diificulty of laying out the transition piece withthe present invention, and with the present invention the outline may besuch as will place the scam on any desired side.

Other objects and advantages will appear in the description and in thedrawings.

In the drawings, Fig. l is a top plan view of a device for use inplotting a transition piece, said device being shown on a sheet ofmaterial with the outline of the end edges of such transition pieceindicated in full line with the different portions the device willoccupy during the plotting of said edges indicated in dash lines.

Fig. 2 is a perspective view of the device of this invention in aposition for initially setting the same for plotting a particulartransition piece adapted to extend between the ends of a rectangularduct and a circular one, portions of the ends of said ducts being shown.

Fig. 3 is a side elevation view of the device of Fig. 2 in position forplotting on fiat sheet.

In detail, the device illustrated in the drawings comprises a centralelongated member, generally designated I, that has a pair of elements 2,3 at its oppositevends to which templates 4, 5 are secured.

The templates 4, 5 are flat pieces of sheet material, such as metal,although they may be of any reasonably rigid material. In the presentinstance the outline of template 4 corresponds to the rectangularoutline of the opening at the end of a duct or conduit 1, such, forexample, as may be at the inlet end of the air duct for a house heatingor air conditioning system. The outline of template 5 corresponds to thecircular outline of the opening at the end of a cylindrical duct orconduit 8, such as may be at the furnace or air circulating means in abuilding. As usually occurs, the conduits I, 8 are not in alignment,although if they were, the present invention would be equallyapplicable. The end edges of ducts l, 8 may or may not be in planesnormal to the central axes of the ducts I, 8, assuming said ducts havestraight end portions. The end edges may be in planes that are at anglesless than relative to the end portions of the ducts. Inany event, theoutlines of the templates normally follow the outlines of the edgesdefining the openings, hence template 5 would not be truly circular ifthe end edges of the duct 8 defining the open end were cut oil at anangle relative to the central axis of the end portion of the duct 8.

The central member I is preferably made up of a central cylindricalsection II an end section I I adjacent the template 4 and an end sectionI2 adjacent the template 5. These end sections H, l2 are tubular fortelescopically receiving therein the end portions H, [2 adjacent theiradjacent ends for rigidly, but releasably, securing said end sections lI 12 to the ends of the central section it against relative rotationbetween said end sections and the central section, and againstlongitudinal movement of said screw l8. adapted to clamp the lug to theflat end portion of the clamping screws.

4, against the plates 20, 30.

3 end sections relative to said central section unless and until it isdesirable to rotate said end sections and to move one or both of saidsections to a new position in longitudinal extension of said centralsection.

The opposite outer end portions i5, id of said sections H, !2respectively, are preferably fiattened longitudinally of said endsections, and said end portions are respectively apertured perpendicularto the central longitudinal axis of eaclli end portion for threadedlyengaging screws ll, 8.

The elements, generally designated 2, 3 are for holding the templates 4,5. The element 2 may comprise a rectangular plate 29 having a centralsubstantially semicircular lug 2! formed on its rear side and projectingperpendicularly from said plate. This lug has fiat sides and is formedwith an opening at the center of its radius adapted to pass screw I1,that, as has been explained, is adapted to threadedly enter the centralopening in the flattened end portion 85 of section II. The head 22 ofsaid screw is adapted to engage said lug for lightening the latteragainst the said end portion I5.

Around the semicircular periphery of lug 2! are radially extendingprotractor graduations 24 having the opening in said lug as the center.Adjacent the periphery of said lug the section II is formed with anindicator 25. Thus, when the plate 26 is perpendicular to the section H,the indicator will point to 90, and if the plate is rotated in onedirection or the other about screw IT as the pivotal point, the readingwill indicate the exact angle between the axis of se tion I l and theplane of plate 23.

Reinforcing ribs 26 are preferably cast on the rear side of plate toinsure against injury to the plate that might cause variations in theplate itself relative to the pivot.

The element 3 may comprise a circular plate 30 having a semicircular lug3! formed on its rear side, said lug 3! being identical with lug 2| andbeing for the same purpose.

Lug 3! is apertured at the center of the radius of the semicircular edgeof said lug for passing Said screw I8 has a head 22 that is indicator onlug 2.

The outer surfaces of the plates 2d, 333 are perfectly flat and each iscentrally provided with a central threaded opening for threadedlyreceiving a screw having a clamping head 36 thereon, each of which mayhave wings for finger operation.

Each template has a central opening for each Thus the head 3'! of eachscrew will releasably clasp the templates To change templates, thescrews are merely removed to release the old templates, and a new one isthen clamped .in place.

provide a support against which the template is clamped, the support andhead of the clamping screw providing the clamping elements. Theperiphery of the template secured thereto will always extend beyond theedges of the plates 20,

unless the plates themselves are used as templates, which would bepossible if they had the correct outlines and, in some instances thismay be the case, since said plates could be changed by removing thescrews ll, it.

Usually templates would be used for the reason that in any shop whereonly several standard transition pieces are made, the likelihood is thattemplates of such pieces would be used instead of attempting to plot outeach piece.

Preferably the central section It has a longitudinally extending line4i] inscribed thereon, or aligned lines may be used only at the ends ofthe central section if desired, leaving the center unmarked. This line Mprovides points at the junctures between end sections II, l2 and saidcentral portion, the ends of said sections at said juncture being formedwith equally spaced graduation marks M in a row extending around theouter ends of said sections. These may be given values that will enablethe user to determine the angular variation between a plane extendingthrough said central mark 4i! (and parallel therewith) and through thecentral axis of the central member iii, and planes respectivelyperpendicular to the axes of pivots ll, l8 and which latter planes alsoextend through the central axis of section ii] and parallel therewith.Screws l3 releasably secure the end sections against rotation relativeto the central section.

In operation, assuming the user wishes to lay out or to plot the endedges of a transition piece that will accurately fit the adjacent openends of the ducts l, B, the first step will be to cut templates t, 5that will substantially correspond with the outlines of the adjacentedges of said ducts, which does not require any great degree of skilland which may be quickly done. Each template is then centrally aperturedand the templates are then secured against plates 20, 30.

The next step is to place the template 5 within the open end of duct 8in a plane substantially perpendicular to the plane in which the endedges of said duct are disposed, and the template 4 is similarly placedwithin the end of duct 7. Screws ll, I8 enable the templates to beangularly adjusted so that they are in planes parallel with the plane inwhich the edges of the end openings of said ducts are disposed, andscrews ll, l8 enable the central member to be extended so that thetemplates will reach said openings, and said latter screws also permitadjustment of the templates should the axes of ducts l, 8 not be in thesame plane. If the distance between the end openings in the ducts is toogreat for the central member I, it is merely necessary to replace thecentral section 10 with one of suitable length.

After the templates are correctly positioned, and. the screws !3, ll, i8are tightened, the device may be placed on the sheet 35 of metal fromwhich the transition piece is to be out.

Any sheet having a transfer surface, such as graphite, carbon, whiting,etc. may be placed between the templates and the sheet of metal to becut.

Upon rolling the device having the templates in the direction of thearrows (Fig. 1) the templates will cause the lines 47, 8 to be formed onthe metal, which lines will accurately define the end edges of thetubular transition piece when the latter is bent to join the ends 59.These end edges will precise-1y follow the contours of the open ends ofthe conduits l, 8. If it is desired that the ends of the transitionpiece extend into the conduits or over the ends of the conduits; it isobvious that the seam to be formed along the edges 48, 49 may beslightly varied and the end edges may be formed on outside lines 41, 48but parallel therewith when cutting the metal.

If desired, the edges of the templates may be chalked or treated tocarry the marking material for marking lines 41, 48, in which case thetransfer paper could be omitted. Or it is relatively simple for anoperator to merely mark the sheet material with a crayon or pencil atthe point of contact between the templates and the plate or sheet as thetemplates are rolled over the sheet. This latter procedure requires careto prevent any slippage of the templates on the sheet since it isusually rolled over the sheet twice in order to mark the path of bothtemplates.

The successive positions of the templates during their movement over thesheet are indicated in dash lines in Fig. 1, and it will be seen thatthe edges 49 are so positioned as to bring the seam on the inside bendof the transition piece when the blank is bent. If it is desired thatthe seam be on the outside, it is only necessary that the templates beinitially positioned on the sheet in the dash line positions 50, andthen one complete revolution of the templates be effected on the sheet.If a side seam is desired, the templates should be started in positions5| or 52 according to the side. The marking commences directly below thecentral member I in each instance and terminates centrally below saidmember, as seen in Fig. 1 irrespective of which side of the transitionpiece is to have the seam.

From the foregoing explanation, it is seen that the outlines and sizesof the openings to be connected by the transition piece are immaterial.The device works in the same manner irrespective of the variations. Nordoes the angular relationship between the planes of the edges of saidopenings make any difference nor the degree or direction of offsetbetween the central axes of the said openings. The simple mechanics ofeither positioning the templates in the openings or at their edges, asdescribed, and then locking them rigid and marking their paths of travelon the sheet, is all that is required to plot with precise accuracy theend edges of the transition piece.

In those instances where it is desired that the transition pieces beformed in advance of the installation of the ducts or the formation ofopenings to be connected, the provision of the protractor markings 24and the graduation 40, 4! enable the user to follow the specificationsand to thus plot the transition pieces without requiring the ducts orthe openings as guides.

It is to be understood that the precise structure above described indetail is not intended to be restrictive of the invention, but is merelya preferred form. It is obvious that the means for securing thetemplates to the ends of the central member I may be varied and that theelements 5, need not be exactly the shapes disclosed. Also the centralmember could be made up of more telescopically connected members thanillustrated to provide for greater extension or shortening. However,such structure ordinarily would increase the cost without any materialbenefit, and would introduce complexities that would be likely to givetrouble or be easily injured. It is a simple matter for the average shopto carry sufficient different length rigid central elements I0 to takecare of any substantial differences in length and the variation providedfor by the telescopic connections between end sections ll, 12 and saidcentral section is adequate for a wide range of lengths.

I claim:

1. A device for plotting on a flat sheet of material the opposite endedges of a transition piece to be subsequently bent to tubular form forfitting said end edges in spaced openings to be connected by saidtransition piece, said device comprising a pair of template clampingelements respectively adapted to engage the opposite sides of a templatefor securing thereto templates respectively formed with outer peripheraledges substantially corresponding in outline and area with the outlinesand areas of said openings, an elongated member, means for pivotallysecuring said elements to the ends of said member for swinging todifierent angular positions relative to the longitudinal axis of saidmember, said member and said element having relatively movable adjoiningportions, one of said portions including protractor graduations markedthereon and the otheradjoining portion including a fixed graduation forindicating in degrees the angularity between the central axis of saidmember and said clamping elements.

2. -A device for plotting on a flat sheet of material the opposite endedges of a transition piece to be subsequently bent to tubular form forfitting said end edges in spaced openings to be connected by saidtransition piece, said device comprising a pair of template clampingelements respectively adapted to engage the opposite sides of a templatefor securing thereto templates respectively formed with outer peripheraledges substantially corresponding in outline and area with the outlinesand areas of said openings, an elongated member, means for pivotallysecuring said elements to the ends of said member for swinging todifferent angular positions relative to the longitudinal axis of saidmember, said member and said element having relatively movably adjoiningportions, one of said portions including protractor graduations markedthereon and the other adjoining portion including a fixed graduation forindicating in degrees the angularity between the central axis of saidmember and said clamping elements, said elongated member having acentral section and opposite end sections, said end sections beingrotatable about the longitudinal axis of said central section andgraduations on the said central section and said end sections at theirjunctures for indicating the degree of rotation of said end sectionsrelative to said central section.

3. A device for plotting outlines of a flat blank for formation of atransition piece adapted to extend between a pair of spaced openingscomprising: a central, elongated spacing member, a pair of end memberstelescopically carried by the opposite ends respectively of said centralmember for adjustable axial movement relative thereto, means forreleasably securing said central member and end members together formovement as a unit, first clamping members swingably securedrespectively to the ends of said end members that are remote from saidcentral member, and second clamping members releasably secured to saidfirst clamping members and adapted to clamp planar, rigid templatesbetween said first and second clamping members.

4. A device for plotting outlines of a flat blank for formation of atransition piece adapted to extend between a pair of spaced openingscomprising: a central, elongated spacing member, a pair of end memberstelescopically carried by the opposite ends respectively of said centralmember for adjustable axial movement relative thereto, means forreleasably securingsaid central member and end :rn'embers together formovement as a unit, first clamping members 'sw'ingably securedrespectively to the ends of said end members that are remote from saidcentral member, and second clamping members releasably secured to saidfirst clamping members and adapted to clamp planar, rigid templatesbetween said first and second clamping members. said first clampingmembers being provided with calibrations to indicate the degree of'angularity between the same and the longitudinal axis of said centralmember.

5. A device for plotting outlines of a fiat blank for formation of atransition piece adapted to extend between a pair of spaced openingscomprising: a central, elongated spacing member, a pair of end memberstelescopically carried by the opposite ends respectively of said centralmember for adjustable axial movement relative thereto, means forreleasably securing said central member and end members together formovement as a unit, first clamping members swingably securedrespectively to the ends of said "end members that are remote from saidcentral member, and second clamping members releasalbly secured to saidfirst clamping members and adapted to clamp planar, rigid templatesbetween said first and second clamping members, said clamping membersincluding screwthreaded elements for so releasably securing said secondclamping members to said first clamping members.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 809,432 Darrschmidt Jan. 9, 1906 984,347 Cardell Feb. 14, 19111,015,423 Cardell Jan. 23, 1912 1,482,186 Fales Jan. '29, 1924 2,431,100Woods 1 Nov. 18, 1947 2,541,808 C'ahill et al. Feb. -13, 1951 2,585,135Klakovioh -1 Feb. 12, 1952 2,624,944 Pujda Jan. 13, .1953

FOREIGN PATENTS Number Country Date 128,677 Germany Mar. 3, 1902 27,794Great Britain 1911 347,410 Germany Jan. 18, 1-922 560,355 Great BritainMar. 31, 1944

